Transparent High-Resistivity Layer for Electrostatic Friction Modulation Over a Capacitive Input Sensor

ABSTRACT

A transparent high-conductivity layer for providing electrostatic feedback to a user of an electronic device. The transparent high-conductivity layer is positioned over a capacitive input sensor and has a resistivity sufficiently high to prevent interference with the capacitive input sensor. As one example, the transparent high-conductivity layer can be formed from a layer of geometrically-separated regions of high-conductivity material. The average distance between geometrically-separated regions can substantially define the resistivity of the transparent high-conductivity layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.16/143,382, filed Sep. 26, 2018, which is a nonprovisional of and claimsthe benefit under 35 U.S.C. 119(e) of U.S. Provisional PatentApplication No. 62/564,941, filed Sep. 28, 2017, the contents of whichare incorporated herein by reference as if fully disclosed herein.

FIELD

Embodiments described herein relate to capacitive input sensors, and inparticular, to capacitive input sensor stacks that incorporate atransparent high-resistivity layer suitable for electrostatic frictionmodulation.

BACKGROUND

An electronic device can include a capacitive input sensor positionedbelow a surface to detect touch or force input to that surface.Conventionally, a capacitive input sensor is positioned below an outerlayer (e.g., glass, sapphire, and so on) that defines the input surface.

In some cases, it may be desirable to position a conductive layer abovethe capacitive input sensor and below the protective dielectric layer.In many cases, however, the conductive layer interferes with theoperation of the capacitive input sensor and, additionally oralternatively, undesirably changes the appearance of the electronicdevice.

SUMMARY

Embodiments described herein generally relate to electronic devicesincorporating a transparent high-resistivity layer for electrostaticfriction modulation. In particular, the transparent high-resistivitylayer is disposed over a capacitive input sensor that, in turn, isdisposed over a display. The transparent high-resistivity layer iscapacitively coupled to the capacitive input sensor such thatground-shifting of the capacitive input sensor drives the transparenthigh-resistivity layer to a voltage sufficient for electrostaticfriction modulation.

The transparent high-resistivity layer can be formed in a number of waysincluding, but not limited to, defining a number ofgeometrically-separated regions of high-conductivity material spacedsufficiently close to enable charge carrier hopping between regions.

BRIEF DESCRIPTION OF THE FIGURES

Reference will now be made to representative embodiments illustrated inthe accompanying figures. It should be understood that the followingdescriptions are not intended to limit the disclosure to a finite set ofpreferred embodiments. To the contrary, it is intended that thefollowing description covers alternatives, modifications, andequivalents as may be included within the scope of the described ordepicted embodiments and as defined by the appended claims.

FIG. 1A depicts an electronic device including a transparenthigh-resistivity layer disposed over a display.

FIG. 1B depicts a plan view of the electronic device of FIG. 1A,depicting the transparent high-resistivity layer in phantom.

FIG. 2A depicts a cross-section of the transparent high-resistivitylayer of FIG. 1B, taken through line A-A.

FIG. 2B depicts another example cross-section of a transparenthigh-resistivity layer, particularly illustrating an anti-reflectivecoating disposed over the transparent high-resistivity layer.

FIG. 3A depicts a detail view of the enclosed circle B-B of thetransparent high-resistivity layer of FIG. 1B, specifically showing acluster of geometrically-separated regions of high-conductivitymaterial.

FIG. 3B depicts a cross-section view of a transparent high-resistivitylayer formed from another example configuration of a cluster ofgeometrically-separated regions of high-conductivity material.

FIG. 3C depicts a cross-section view of a transparent high-resistivitylayer formed from another example configuration of a cluster ofgeometrically-separated regions of high-conductivity material.

FIG. 3D depicts a cross-section view of a transparent high-resistivitylayer formed from another example configuration of a cluster ofgeometrically-separated regions of high-conductivity material.

FIG. 3E depicts a cross-section view of a transparent high-resistivitylayer formed from another example configuration of a cluster ofgeometrically-separated regions of high-conductivity material.

FIG. 3F depicts a cross-section view of a transparent high-resistivitylayer formed from another example configuration of a cluster ofgeometrically-separated regions of high-conductivity material.

FIG. 4A depicts a cross-section view of a cluster ofgeometrically-separated regions of high-conductivity material having aselected impurity/doping concentration.

FIG. 4B depicts a cross-section view of a cluster ofgeometrically-separated regions of high-conductivity material having aselected impurity/doping concentration.

FIG. 4C depicts a cross-section view of a cluster ofgeometrically-separated regions of high-conductivity material havingmultiple selected impurity/doping concentrations.

FIG. 5A depicts a cross-section view of a transparent high-resistivitylayer formed from a substantially continuous layer of high-conductivitymaterial having a selected impurity/doping concentration.

FIG. 5B depicts a cross-section view of a transparent high-resistivitylayer formed from multiple layers of high-conductivity material, eachhaving a selected impurity/doping concentration.

FIG. 5C depicts a cross-section view of another transparenthigh-resistivity layer formed from multiple layers of high-conductivitymaterial, each having a selected impurity/doping concentration.

FIG. 6A depicts a cross-section view of a layer of high-conductivitymaterial having a selected impurity/doping concentration.

FIG. 6B depicts a cross-section view of a layer of high-conductivitymaterial having a gradient impurity/doping concentration.

FIG. 6C depicts a cross-section view of a layer of high-conductivitymaterial having a surface depth-dependent impurity/doping concentration.

FIG. 6D depicts a cross-section view of a layer of high-conductivitymaterial having multiple discrete regions of selected impurity/dopingconcentrations.

FIG. 7 is a flowchart depicting example operations of a method offorming a transparent high-resistivity layer, such as described herein.

FIG. 8 is a flowchart depicting example operations of a method offorming a transparent high-resistivity layer with selectedimpurity/doping concentrations, such as described herein.

FIG. 9 is a flowchart depicting example operations of a method offorming a transparent high-resistivity layer, such as described herein.

The use of the same or similar reference numerals in different figuresindicates similar, related, or identical items.

The use of cross-hatching or shading in the accompanying figures isgenerally provided to clarify the boundaries between adjacent elementsand also to facilitate legibility of the figures. Accordingly, neitherthe presence nor the absence of cross-hatching or shading conveys orindicates any preference or requirement for particular materials,material properties, element proportions, element dimensions,commonalities of similarly illustrated elements, or any othercharacteristic, attribute, or property for any element illustrated inthe accompanying figures.

Additionally, it should be understood that the proportions anddimensions (either relative or absolute) of the various features andelements (and collections and groupings thereof) and the boundaries,separations, and positional relationships presented therebetween, areprovided in the accompanying figures merely to facilitate anunderstanding of the various embodiments described herein and,accordingly, may not necessarily be presented or illustrated to scale,and are not intended to indicate any preference or requirement for anillustrated embodiment to the exclusion of embodiments described withreference thereto.

DETAILED DESCRIPTION

Embodiments described herein reference an electronic device, such as atablet or smart phone, that includes a high-resistivity layer disposedover a capacitive input sensor disposed, in turn, over a display. Theelectronic device is configured to drive the high-resistivitylayer—either capacitively or conductively—with a suitable high-voltagealternating current signal to modulate perceived friction viaelectrostatic attraction between an exterior surface of the electronicdevice (herein, the “interface surface”) and a user touching thatsurface. As a result of this construction, the user can directlyinteract with contact shown on the display, while receiving localized(or generalized) output in the form of a perceivable variation infriction across the interface surface.

A high-resistivity layer, such as described herein, can be formed in anumber of ways to exhibit any selected resistivity and any selectedoptical characteristic, including optical transparency (e.g., high totaltransmittance) suitable for positioning over, but not obscuring, adisplay. For embodiments described herein, the resistivity of ahigh-resistivity layer is typically selected such that the layer doesnot substantially interfere with the operation of a capacitive inputsensor positioned below it. In addition, the total transmittance of ahigh-resistivity layer is typically selected such that the layer doesnot substantially obscure, distort, or otherwise interfere with adisplay positioned below it. More specifically, a “transparent” layer,such as described herein, may be characterized by a high percentagetransmittance of light (e.g., 50%-100% transmittance) in a traditionallyvisible spectrum (e.g., between 300 nm and 700 nm wavelengths). In manycases, a layer such as described herein can exhibit a transmittancegreater than eighty percent.

As such, for simplicity of description, high-resistivity layersdescribed herein are referred to as “transparent high-resistivitylayers.” It is appreciated, however, that a high-resistivity layer incertain embodiments need not be optically transparent, and can be opaqueor translucent, or may be doped or coated with a pigment to exhibit aparticular color, image, or pattern.

As noted above, a transparent high-resistivity layer, such as describedherein, can be formed in a number of ways. For example, a transparenthigh-resistivity layer can be formed from a conductive material having asuitable resistivity and a suitable transmittance (e.g., metal oxide)disposed to a suitable thickness. More particularly, the conductivematerial is disposed to a selected thickness such that the layerexhibits both high transmittance (e.g., a total transmittance such as50%, 75%, 90%, and so on) and high resistivity (e.g., a sheet resistancesuch as 500 kΩ/sq, 1MΩ/sq, 5MΩ/sq, 10MΩ/sq, 20MΩ/sq). In thisconstruction, the thickness of the conductive material layer maysubstantially define both the transmittance and the resistivity of thelayer; modifying the thickness of the layer—which may be substantiallycontinuous or variable across the surface of the layer—can serve toeither increase or decrease the transmittance and/or resistivity.Different embodiments may be implemented with conductive layers ofdifferent thicknesses.

In another example, a transparent high-resistivity layer can include anumber of geometrically-separated regions of transparenthigh-conductivity material, such as indium-tin oxide. The distancebetween individual regions of the high-conductivity material istypically small in order to facilitate charge carrier hopping fromregion to region. As a result of this construction, the average distancebetween individual regions of high-conductivity material can becorrelated to resistivity of the layer. For example, the greater theaverage distance between regions, the more the resistivity of the layerincreases.

In some embodiments, all regions of high-conductivity material defininga transparent high-resistivity layer can be formed to take substantiallythe same shape and can be formed to substantially the same thickness. Inother embodiments, different regions are formed to different thicknessesand/or different shapes. In some embodiments, multiple sublayers ofregions of high-conductivity material can be layered on one another.

In still further embodiments, a substantially continuous layer of dopedhigh-conductivity material can be used to form a high-resistivity layer.For example, a doped layer of indium-tin oxide (or another metal oxide)can be used. Doping concentrations and dopant locations can change fromembodiment to embodiment. For example, in some embodiments, a highdopant concentration corresponds to a higher resistance than a lowdopant concentration. In other examples, a dopant gradient can bedefined through a thickness of the layer. More particularly, localconcentration of dopant material may increase or decrease as a functionof depth into the thickness of the high-conductivity material.

The foregoing example constructions of a transparent high-resistivitylayer are not exhaustive. It may be appreciated that in furtherembodiments, other configurations (e.g., multilayer, single layer,doping gradients, doping profiles, and so on) and materials (e.g.,silicon oxides, aluminum oxides, zinc oxides, tin oxides, doped tinoxide, Iridium doped tin oxide, doped indium oxide, titanium oxides,nitrides, oxynitrides, sulfides, substoichiometric oxides, nitrides oroxynitrides; mixed metal oxides, doped oxides, inorganic perovskites,cation or anion deficient metal oxides, nitrides, oxynitrides orsulfides; metal nanoparticles or metal impurities in an oxide structure,and so on) are possible. For example, in an embodiment, silicon dioxidecan be combined with tin dioxide (e.g., SiO₂₊SnO₂).

More generally, independent of construction, a transparenthigh-resistivity layer is typically disposed above a capacitive inputsensor which, in turn, is disposed above a display of an electronicdevice. The electronic device is configured to drive the transparenthigh-resistivity layer with a high voltage signal in order to increaseperceived friction between the user's finger and the interface surfaceabove (or defined by) the transparent high-resistivity layer.

Typically, a separator layer conductively isolates the transparenthigh-resistivity layer from the capacitive input sensor. The separatorlayer can be a single layer of dielectric material (e.g., glass,adhesive, polymer, and so on) or more than one sublayers of dielectricmaterial. In some embodiments, the separator layer can include one ormore circuits or circuit traces, such as thin-film transistor circuits.Example capacitive input sensors include, but are not limited to,capacitive touch input sensors (e.g., projected capacitance,single-touch, multi-touch, mutual capacitance, self-capacitance, and soon) and capacitive force sensors (e.g., gap-based compression sensors,capacitive strain sensors, single-force, multi-force, binary force,variable force, and so on).

The electronic device can drive the transparent high-resistivity layerusing any suitable technique. For example, in one embodiment, aprocessor of the electronic device is conductively coupled to thetransparent high-resistivity layer and is configured apply ahigh-voltage drive signal to the transparent high-resistivity layer(e.g., 600 Vpp, 500 Vpp, 400 Vpp, and so on).

In another embodiment, a processor of the electronic device iscapacitively coupled to the transparent high-resistivity layer via thecapacitive input sensor. In this embodiment, the electronic device isconfigured to ground-shift the capacitive input sensor according to ahigh-voltage drive signal. In other words, the electronic devicesupplies a signal-modulated local ground and a signal-modulated localsource to the sensor with a constant direct current offset between thelocal ground and the local source.

As a result of this construction, the capacitive input sensor operatesacross the constant direct current offset and the alternating currentcomponents of the high-voltage drive signal are capacitively coupledinto the transparent high-resistivity layer. As a result of thecapacitive coupling between the transparent high-resistivity and thecapacitive input sensor, the user may perceive increased friction due toelectrostatic attraction. In other words, the user may perceive certainregions of the interface surface as having different friction than otherregions. Certain regions may be perceived to be high friction regionswhereas other regions may be perceived to be low friction regions.

These and other embodiments are discussed below with reference to FIGS.1A-9. However, those skilled in the art will readily appreciate that thedetailed description given herein with respect to these figures is forexplanatory purposes only and should not be construed as limiting.

Generally and broadly, FIGS. 1A-1B depict an electronic device 100 thatincorporates a transparent high-resistivity layer (see, e.g., FIG. 1B)positioned relative to an interface surface that may be touched by auser. The interface surface of the electronic device 100 is defined by ahousing 102 that encloses, below the interface surface, a display 104and a capacitive input sensor (not shown). The transparenthigh-resistivity layer 106 is shown in phantom in FIG. 1B.

In the illustrated embodiment, the electronic device 100 is depicted asa tablet computer, although this may not be required of all embodimentsand the electronic device can take other forms such as, but not limitedto: cellular phones; multi-screen tablet computers; desktop computers;wearable electronic devices; peripheral input devices; console controlsystems; industrial control devices; medical devices; diagnosticdevices; vehicle or aeronautical control or entertainment systems; andso on.

As noted above, the display 104 is within the housing 102 and positionedbehind the interface surface. The display 104 may include, or can beassembled from, a stack of multiple layers or elements including, forexample, a display element, a touch sensor layer, a force sensor layer,a color filter layer, a polarizer layer, an anode layer, a cathodelayer, an encapsulation layer, and other elements or layers. The display104 may include a liquid-crystal display element, organic light emittingdiode element, electroluminescent display, and the like. The display 104may also include other layers for improving the structural or opticalperformance of the display, including, for example, glass sheets,polymer sheets, polarizer sheets, adhesive layers, color masks, and thelike. The display 104 can be integrated into or incorporated with acover that at least partially defines the interface surface of theelectronic device 100. In many examples, the cover is formed from glassor another suitable material such as plastic, sapphire, ion-implantedglass, and so on. In some cases, the cover is a solid material whereasin other cases the cover is formed by laminating or adhering severalsublayers of material together. In some embodiments, the cover can becoated with an antireflective and/or oleophobic coating.

The input sensor of the electronic device 100 can be configured todetect various capacitances associated with combinations of user touchand/or force input on the interface surface. More particularly, theinput sensor can be configured to detect the location of a touch, amagnitude and/or direction of a force exerted, and/or a movement of atouch or a force input on the interface surface. In some examples, theinput sensor can be configured to detect more than one touch inputand/or more than one force input simultaneously. Additionally, the inputsensor can be used separately or in combination with other sensors orsystems of the electronic device 100 to detect and/or interpret a broadrange of user inputs such as, but not limited to, touch-based gestures,force-based gestures, touch patterns, tap patterns, single-fingergestures, multi-finger gestures, multi-force gestures, and so on.

The input sensor can be implemented in any number of suitable ways withany suitable capacitive sensing technology or combination oftechnologies including, but not limited to, self-capacitancetouch-sensing, mutual capacitance touch-sensing, capacitive forcesensing, and so on, or any combination thereof.

Some embodiments include multiple input sensors. The input sensors canbe independently addressable and may be distributed and/or segmentedacross the display 104. In other embodiments, the input sensors may bedisposed relative to a perimeter of the display 104. In suchembodiments, the input sensors may be disposed below an opaque ortranslucent bezel surrounding the display 104. The bezel can take anysuitable shape and is not limited to a single color, location,translucency, or transparency. In some cases, the bezel can wrap aroundone or more sidewalls or edges of the housing 102. In some cases, thebezel can selectively obscure a secondary display, a biometric sensor,an imaging sensor, an input sensor, a button, and so on.

As noted above, in many embodiments, the input sensor can beground-shifted and capacitively coupled to the transparenthigh-resistivity layer 106. In this manner, the electronic device 100can drive the transparent high-resistivity layer 106 to a high voltagein order to electrostatically attract the user's finger, inducing aperceivable friction between the user and the interface surface.

More generally, as a result of this arrangement, the electronic device100 can provide output in the form of variable friction to the user, viathe transparent high-resistivity layer 106, when the user touches and/orapplies a purposeful force to the interface surface. The output may belocalized to a particular region of the interface surface, or may beprovided across the entire interface surface.

In some cases, more than one output may be provided at the same time. Ifthe user touches a first location of the interface surface above thedisplay 104, the user may perceive a first output. If the user touches asecond location of the display 104, the user may perceive a secondoutput. If the user drags a finger from the first location to the secondlocation, the user may perceive a transition, which may be abrupt orgradual, between the first output and the second output. In furtherembodiments, a boundary or border between the first location and thesecond location may be associated with yet a third output.

The foregoing description of the embodiment depicted in FIGS. 1A-1B, andvarious alternatives thereof and variations thereto are presented,generally, for purposes of explanation, and to facilitate a thoroughunderstanding of the detailed embodiments presented herein. However, itwill be apparent to one skilled in the art that some of the specificdetails presented herein may not be required in order to practice aparticular described embodiment, or an equivalent thereof.

Thus, it is understood that the foregoing and following descriptions ofspecific embodiments of an electronic device incorporating a transparenthigh-resistivity layer are presented for the limited purposes ofillustration and description. These descriptions are not targeted to beexhaustive or to limit the disclosure to the precise forms recitedherein. To the contrary, it will be apparent to one of ordinary skill inthe art that many modifications and variations are possible in view ofthe above teachings.

Generally and broadly, FIGS. 2A-2B depict cross-sections of thetransparent high-resistivity layer of FIG. 1B, such as described herein.

FIG. 2A depicts a cross-section 200 a that includes a transparenthigh-resistivity layer, such as depicted in FIG. 1B through section A-A.The cross-section 200 a depicts a stack of layers, each of which may beformed from one or more materials and may be conductive, dielectric, orsemi-conductive. More specifically, the cross-section 200 a includes acapacitive input sensor 202 separated from a transparenthigh-resistivity layer 204 by a dielectric layer 206 formed from one ormore layers of material such as, but not limited to: glass; acrylic;sapphire; ceramic; polymers; organic materials; and so on. Thecapacitive input sensor 202, the dielectric layer 206, and thetransparent high-resistivity layer 204 are each optically transparentand are disposed over a display 208. In this example, the transparenthigh-resistivity layer 206 is capacitively coupled to the capacitiveinput sensor 202, which—in one embodiment—can be ground-shifted in orderto capacitively drive the transparent high-resistivity layer 206 with ahigh voltage signal.

In further embodiments, such as illustrated in the cross-section 200 bdepicted in FIG. 2B, the transparent high-resistivity layer 204 canaccommodate (e.g., chemically or mechanically bond to) an outer layer210. In some embodiments, the outer layer 210 is a passivation layerthat protects the transparent high-resistivity layer 204 from oxidationdamage. In other cases, the outer layer 210 is an encapsulation layerthat protects the transparent high-resistivity layer 204 fromenvironmental or impact damage. In still other cases, the outer layer210 is an antireflective layer that improves the performance and/orappearance of the display 208. In other cases, the outer layer 210 is anoleophobic or hydrophobic layer. In some embodiments, the outer layer210 can perform more than one function.

In typical examples, the various layers of the stack depicted in thecross-section 200 a and the cross-section 200 b are chemically adheredto one another and/or with one or more layers of optically clearadhesive. In other cases, the various layers of the stack depicted inthe cross-section 200 a and/or the cross-section 200 b are laminatedtogether. In still further examples, the various layers of the stackdepicted in the cross-section 200 a and/or the cross-section 200 b aremechanically fastened to one another using a suitable technique such as,but not limited to: laser welding; sonic welding; a perimeter ring orframe; mechanical fasteners; clamps; and so on or any combinationthereof.

The transparent high-resistivity layer 204 can be formed from any numberof materials or combination of materials. Several example constructionsare provided herein, but it may be appreciated that these examples arenot exhaustive and that a high-resistivity layer can be constructed,shaped, disposed, formed, or otherwise structured in any number ofsuitable and/or implementation-specific ways.

For example, in one embodiment, the transparent high-resistivity layer206 is formed from a number or cluster of geometrically-separatedregions of high-conductivity material (see, e.g., FIGS. 3A-4C), such asa transparent metal oxide. The geometrically-separated regions ofhigh-conductivity material can be formed in a number of suitable waysincluding, but not limited to: deposition; mask and etch; laser etching;chemical etching; mechanical etching; vapor deposition, sputtering,metasputtering, reactive sputtering, thermal ablation, e-beamevaporation, printing, gravure, roll-to-roll deposition; and so on orany combination thereof. In this construction, the separation anduniformity of the geometrically-separated regions of high-conductivitymaterial can define the resistivity and transmittance of thehigh-resistivity layer 206.

In further embodiments, the transparent high-resistivity layer 206 isformed from multiple sublayers of material, some of which may have highresistivity and some of which may have low resistivity (see, e.g., FIGS.5A-5C). In this construction, the conductivity and transmittance of thevarious sublayers can define the resistivity and transmittance of thehigh-resistivity layer 206.

In still further embodiments, the transparent high-resistivity layer 206is formed from a doped transparent conductive metal oxide (see, e.g.,FIGS. 6A-6D) using a suitable technique such as, but not limited to,vapor deposition, printing, gravure, roll-to-roll deposition, and so on.Example metal oxides include but are not limited to: indium oxides,gallium oxides, aluminum oxides, titanium oxides, zinc alloy oxides;zinc-doped tin oxide; indium-tin alloy oxides; and so on, or anycombination thereof. In this construction, dopant concentrations—whetherlocal, global, gradient, or depth-dependent—can define the resistivityand transmittance of the transparent high-resistivity layer 206.

Independent of a selected construction, and as noted above, thetransparent high-resistivity layer 204 typically has a sheet resistanceof 500 kΩ/sq, 1MΩ/sq, 5MΩ/sq, 10MΩ/sq, 20MΩ/sq, or higher. Also as notedabove, a higher sheet resistance may be selected so that the transparenthigh-resistivity layer 204 does not substantially interfere with theoperation of the capacitive input sensor 202.

As noted with respect to other embodiments described herein, in someexamples, the capacitive input sensor 202 is a touch input sensorconfigured to measure for changes in capacitance between a first set ofelectrodes (not shown) and a second set of electrodes (not shown) thatmay result from the proximity of a user's finger or another inputobject, such as a stylus. The capacitive input sensor 202 can operate asa single-touch or multi-touch input sensor.

In other embodiments, the capacitive input sensor 202 is a force inputsensor configured to measure for changes in capacitance between a firstset of electrodes and a second set of electrodes that may result fromcompression of the dielectric layer 206. For example, the dielectriclayer 206 can be formed from an elastic material or may include acompressible air gap.

In still further examples, the capacitive input sensor 202 may be acombined sensor in which a first set of electrodes are configured todetect touch input via projected capacitance and a second set ofelectrodes are configured to detect force input via strain-basedresistance, inductance, charge, or capacitances measurements. In thismanner, changes in an electrical property of a first set of electrodesand/or a second set of electrodes can be correlated to a magnitude offorce applied by a user to the interface surface.

The foregoing description of the embodiment depicted in FIGS. 2A-2B, andvarious alternatives thereof and variations thereto are presented,generally, for purposes of explanation, and to facilitate a thoroughunderstanding of the detailed embodiments presented herein. However, itwill be apparent to one skilled in the art that some of the specificdetails presented herein may not be required in order to practice aparticular described embodiment, or an equivalent thereof.

Thus, it is understood that the foregoing and following descriptions ofspecific embodiments of a stack of layers including a transparenthigh-resistivity layer are presented for the limited purposes ofillustration and description. These descriptions are not targeted to beexhaustive or to limit the disclosure to the precise forms recitedherein. To the contrary, it will be apparent to one of ordinary skill inthe art that many modifications and variations are possible in view ofthe above teachings.

Generally and broadly, FIGS. 3A-3F depict various detail views ofexample cross-sections of a transparent high-resistivity layer, such asdepicted in FIG. 2B in the enclosed circle B-B. In general, theseembodiments depict a transparent high-resistivity formed from a numberor cluster of geometrically-separated regions of high-conductivitymaterial. As noted above, the distance between individual regions of thehigh-conductivity material is typically small in order to facilitatecharge carrier hopping from region to region, facilitating conductionacross the layer. As a result of this construction, the average distancebetween individual regions of high-conductivity material can becorrelated to resistivity of the layer. For example, the greater theaverage distance between regions, the more the resistivity of the layerincreases. In some examples, the separation between individual regionsmaybe on the order of 1-5 nm.

In particular, FIG. 3A depicts a detail view 300 a of a transparenthigh-resistivity layer defined by a cluster of geometrically-separatedregions of high-conductivity material, one of which is identified as theregion 302. As with the embodiment described in reference to FIGS.2A-2B, the region 302 can be disposed onto, formed onto, or otherwiseattached to a dielectric layer 304.

The region 302—along with the other geometrically-separated regions ofhigh-conductivity and optically transparent material—can be formed in anumber of suitable ways from a number of suitable materials orcombinations of materials. In one embodiment, the region 302 is formedentirely from a transparent metal oxide, such as indium tin oxide. Inanother embodiment, the region 302 is formed from a low-conductivitymaterial, such as aluminum oxide, that is doped with a high-conductivitymaterial, such as indium tin oxide. In other cases, the region 302 isformed from a cured sol of conductive material, such as a profusion ofmetal nanowires suspended in a curable adhesive.

In many embodiments, the region 302 and the other geometrically-separateregions have the same height and/or thickness. It may be appreciatedthat this is not required and, in some embodiments, certain regions mayhave a different height/thickness than other regions.

In many embodiments, the region 302 and the other geometrically-separateregions have the same shape. As shown the region 302 takes asubstantially rounded or dome shape. It may be appreciated that this isnot required and, in some embodiments, certain regions may have adifferent shape. For example, in some embodiments, thegeometrically-separated regions of high conductive material can take theshape of, without limitation: a rectangle; a square; a roundedrectangle; a serpentine shape; a concentric set of shapes (e.g.,concentric circles, concentric squares, and so on); a tessellated shape;and so on or any combination thereof.

The cross-section 300 a also depicts an outer layer 306 is disposed overthe region 302. As noted above, the outer layer 306 can be a passivationlayer, an antireflective layer, an oleophobic layer, a hydrophobiclayer, an encapsulation layer, or any other suitable layer. Asillustrated, the outer layer 306 occupies space between thegeometrically-separated regions, but this may not be required. Forexample, in some embodiments, a filler material can be disposed tooccupy the space between the geometrically-separated regions. In theseexamples, the outer layer 306 can be disposed over the filler material.

As noted with respect to other embodiments described herein, thedistance between the region 302 and adjacent regions of thehigh-conductivity material is typically small in order to facilitatecharge carrier hopping from region to region. As a result of thisconstruction, the average distance between individual regions ofhigh-conductivity material can be correlated to resistivity of thelayer. For example, the greater the average distance between regions,the more the resistivity of the layer increases.

More particularly, the average distance between regions as shown in thedetail view 300 a is greater than the average distance between regionsshown in the detail view 300 b of FIG. 3B. As such, the sheet resistanceof the transparent high-resistivity layer depicted in detail view 300 amay be less than the sheet resistance of the high-resistivity layerdepicted in detail view 300 b. As another example, the, average distancebetween regions as shown in the detail view 300 a is less than theaverage distance between regions shown in the detail view 300 c of FIG.3C. As such, the sheet resistance of the transparent high-resistivitylayer depicted in detail view 300 a may be less than the sheetresistance of the high-resistivity layer depicted in detail view 300 c.

As noted above, in FIGS. 3A-3C, the region 302 is shown as taking arounded shape. However this particular cross-sectional shape is notrequired and other embodiments can include region(s) have differentshapes. For example, in some embodiments, differentgeometrically-separated regions can be shaped differently. FIG. 3Ddepicts a cross-section 300 d showing differently-sized regions. Inparticular, a small region 308 can be positioned adjacent to a largeregion 310. In addition, in this embodiment, the regions have a smallerthickness than the regions depicted in FIGS. 3A-3C. In thiscross-section, the outer layer 306 may be disposed to a greaterthickness than the outer layer 306 as shown in FIGS. 3A-3C. However,this may not be required. For example, as shown in the cross-section 300e of FIG. 3D, the outer layer 306 can be disposed to a smaller thicknessthan the outer layer 306 depicted in FIGS. 3A-3D. In addition, as shownin the cross-section 300 e, a region 312 can be disposed to besubstantially flat. In some examples, the region 312 can take aflattened dome shape with rounded edges or sidewalls.

The foregoing description of the embodiment depicted in FIGS. 3A-3E, andvarious alternatives thereof and variations thereto are presented,generally, for purposes of explanation, and to facilitate a thoroughunderstanding of the detailed embodiments presented herein. However, itwill be apparent to one skilled in the art that some of the specificdetails presented herein may not be required in order to practice aparticular described embodiment, or an equivalent thereof. For example,in some embodiments, the geometrically-separated regions ofhigh-conductivity material can be disposed at a higher density thandepicted. FIG. 3F depicts a cross-section 300 f, showing a greaternumber of smaller regions than shown in the cross-section 300 a of FIG.3A.

Accordingly, it is understood that the foregoing and followingdescriptions of specific embodiments of a high-resistivity layer formedby geometrically separated regions of high-conductivity material arepresented for the limited purposes of illustration and description.These descriptions are not targeted to be exhaustive or to limit thedisclosure to the precise forms recited herein. To the contrary, it willbe apparent to one of ordinary skill in the art that many modificationsand variations are possible in view of the above teachings.

In other embodiments, a transparent high-resistivity layer can be formedin another manner. For example, generally and broadly, FIGS. 4A-4Cdepict various detail views of example cross-sections of a transparenthigh-resistivity layer. In general, these embodiments depict atransparent high-resistivity formed from a number or cluster ofgeometrically-separated regions of material having differentconcentrations of high-conductivity dopant. As noted above, the distancebetween individual regions is typically small in order to facilitatecharge carrier hopping from region to region, facilitating conductionacross the layer. As a result of this construction, the average distancebetween individual regions can be correlated to resistivity of thelayer. For example, the greater the average distance between regions,the more the resistivity of the layer increases. Similarly, the greaterthe concentration of high-conductivity of dopant, the more theresistivity of the layer decreases.

In particular, FIG. 4A depicts a detail view 400 a of a transparenthigh-resistivity layer defined by a cluster of geometrically-separatedregions, one of which is identified as the region 402. As with theembodiment described in reference to FIGS. 2A-2B and 3A-3C, the region402 can be disposed onto, formed onto, or otherwise attached to adielectric layer 404.

The region 402—along with the other geometrically-separated regions ofhigh-conductivity and optically transparent material—can be formed in anumber of suitable ways from a number of suitable materials orcombinations of materials. In one embodiment, the region 402 is formedfrom a low conductivity body doped with a high-conductivity dopant 406.The high-conductivity dopant 406 can be formed from any number ofsuitable materials such as, but not limited to: a transparent metaloxide, such as indium tin oxide; a metal nanowire, such as a silvernanowire; and so on. In the illustrated embodiment, thehigh-conductivity dopant 406 is disposed to a selected concentration C₁.

As with the embodiments described in reference to FIGS. 3A-3F, in manyembodiments, the region 402 and the other geometrically-separate regionshave the same height and/or thickness. It may be appreciated that thisis not required and, in some embodiments, certain regions may have adifferent height/thickness than other regions. Similarly, the region 402and the other geometrically-separate regions have the same shape and/ordopant concentration. As shown the region 402 takes a substantiallyrounded shape. It may be appreciated that this is not required and, insome embodiments, certain regions may have a different shape. Forexample, in some embodiments, the geometrically-separated regions ofhigh conductive material can take the shape of, without limitation: arectangle; a square; a rounded rectangle; a serpentine shape; aconcentric set of shapes (e.g., concentric circles, concentric squares,and so on); a tessellated shape; and so on or any combination thereof.

As with other embodiments described herein, the detail view 400 a alsodepicts an outer layer 408 is disposed over the region 402. As notedabove, the outer layer 408 can be a passivation layer, an antireflectivelayer, an oleophobic layer, a hydrophobic layer, an encapsulation layer,or any other suitable layer. As illustrated, the outer layer 408occupies space between the geometrically-separated regions, but this maynot be required. For example, in some embodiments, a filler material canbe disposed to occupy the space between the geometrically-separatedregions. In these examples, the outer layer 408 can be disposed over thefiller material.

As noted with respect to other embodiments described herein, thedistance between the region 402 and adjacent regions is typically smallin order to facilitate charge carrier hopping from region to region. Asa result of this construction, the average distance between individualregions can be correlated to resistivity of the layer. For example, thegreater the average distance between regions, the more the resistivityof the layer increases.

In other embodiments, other concentrations of dopant can be used. Forexample, as shown in the cross-section 400 b of FIG. 4B thehigh-conductivity dopant 406 can be disposed to a higher concentrationC₂. In still further embodiments, different regions can have differentconcentrations, such as shown in cross-section 400 c of FIG. 4C.

The foregoing description of the embodiment depicted in FIGS. 4A-4F, andvarious alternatives thereof and variations thereto are presented,generally, for purposes of explanation, and to facilitate a thoroughunderstanding of the detailed embodiments presented herein. However, itwill be apparent to one skilled in the art that some of the specificdetails presented herein may not be required in order to practice aparticular described embodiment, or an equivalent thereof.

Accordingly, it is understood that the foregoing and followingdescriptions of specific embodiments of a high-resistivity layer formedby geometrically separated regions of low-conductivity material dopedwith high-conductivity material are presented for the limited purposesof illustration and description. These descriptions are not targeted tobe exhaustive or to limit the disclosure to the precise forms recitedherein. To the contrary, it will be apparent to one of ordinary skill inthe art that many modifications and variations are possible in view ofthe above teachings.

In still further embodiments, as noted above, a transparenthigh-resistivity layer can be formed from a substantially contiguouslayer (or more than one layer) of material. The layer can be formed froma single material or multiple materials. In particular, FIGS. 5A-6Ddepict various configurations of a transparent high-resistivity layerformed from a substantially contiguous layer. In particular, FIG. 5Adepicts a cross-section 500 a including a dielectric layer 602, atransparent high-resistivity layer 504, and an outer layer 506.

As described with respect to other embodiments herein, the dielectriclayer 502 can be formed from a single layer or multiple layers, and canbe formed from, without limitation: glass, plastic, acrylic, polymer,ceramic, and so on. In some cases, the dielectric layer 502 also servesas an outer layer of a display, such as the display 104 shown in FIG.1A. In still further examples, the dielectric layer 502 can be afunctional layer of a display, such as an encapsulation layer of anorganic light emitting diode display or a polarizer layer of a liquidcrystal display.

Also as described with respect to other embodiments herein, the outerlayer 506 can be a passivation layer, an encapsulation layer, aprotective layer, and so on, and can be made from any number of suitablematerials. In some cases, the outer layer 506 may not be required.

In this embodiment, the transparent high-resistivity layer 504 can beformed from a low-conductivity material doped with a high conductivitydopant, such as metal nanowire or a transparent conductive oxide. Asnoted above, the thickness of the transparent high-resistivity layer 504may be related to the resistivity of the layer. Accordingly, differentembodiments may include a transparent high-resistivity layer 504 ofdifferent thicknesses. Generally, a thinner layer may be associated withhigher resistivity, but this may not be required of all embodiments.

In further examples, a transparent high-resistivity layer can beimplemented with one or more sublayers of conductive or resistivematerial. For example, FIG. 5B depicts a cross-section 500 b that, likethe cross-section 500 a, includes a dielectric layer 502, a transparenthigh-resistivity layer 504, and an (optional) outer layer 506. In thisexample, the transparent high-resistivity layer 504 includes threedistinct sublayers. A first high-conductive sublayer 508 and a secondhigh-conductivity sublayer 510 can be disposed on opposite sides of alow-conductivity sublayer 512. Suitable materials for thehigh-conductivity sublayers 508, 510 include, but are not limited to,metal oxides. Suitable materials for the low-conductivity sublayer 512include, but is not limited to, low-conductivity oxides such as aluminumoxide. Although only three sublayers are shown, it is appreciated thatany suitable number of sublayers may be included.

In still further embodiments, a transparent high-resistivity layer canbe implemented with a high number of sublayers. For example, FIG. 5Cdepicts a cross-section 500 c that includes a transparenthigh-resistivity layer 504 implemented with numerous sublayers ofmaterial, each having a selected conductivity/resistivity. In someexamples, the sublayers can alternate from a first conductivity to asecond conductivity. In other examples, the sublayers can progressivelyincrease or decrease in conductivity to define a gradient conductivity.In still further examples, each sublayer can have a selectedconductivity different from the conductivities of adjacent or othersublayers. The foregoing examples are not exhaustive; it may beappreciated that any suitable layering configuration may be appropriatefor a particular implementation.

In still further embodiments, a substantially contiguous layer ofmaterial defining a transparent high-resistivity layer can be formedfrom a low-conductivity material doped with a high-conductivity dopant.In other examples, a high-conductivity material can be doped with alow-conductivity dopant. For simplicity of description, the embodimentsthat follow reference a low-conductivity material doped with ahigh-conductivity dopant, but it is appreciated that this is merely anexample.

For example, FIG. 6A depicts a cross-section 600 a that includes adielectric layer 602, a transparent high-resistivity layer 604, and anouter layer 606. In this example, the transparent high-resistivity layer604 includes a body 608 and a dopant 610. The dopant 610 can be disposedin a substantially uniform manner throughout the body 608 so as todefine a substantially consistent sheet resistance for the transparenthigh-resistivity layer 604.

In other cases, a dopant gradient can be used. For example, FIG. 6Bdepicts a cross-section 600 b in which the transparent high-resistivitylayer 604 includes multiple dopant concentrations defining a gradientthrough the thickness of the transparent high-resistivity layer 604. Inparticular, a first side of the transparent high-resistivity layer 604abutting the outer layer 606 can have a first dopant concentration 612than a second side of the transparent high-resistivity layer 604abutting the dielectric layer 602 can have a second dopant concentration614.

In still further embodiments, horizontal or vertical dopant bands can beused. For example, FIG. 6C depicts a cross-section 600 c in which thetransparent high-resistivity layer 604 includes multiple dopantconcentration bands generally horizontally aligned. In particular, twobands of a first dopant concentration 612 can be positioned parallel toa third band of a second dopant concentration 614. In other cases,dopant concentration bands can be oriented along a different directionthan depicted in FIG. 6C, such as along an angle, following a zig-zagpattern, vertically-aligned, and so on.

In still further embodiments, dopant bands can separated by dopant-freeregions of the body of the transparent high-resistivity layer 604. Forexample, FIG. 6D depicts a cross-section 600 d in which the transparenthigh-resistivity layer 604 includes two dopant bands having a firstdopant concentration 612 separated by a dopant-free region (alsoreferred to as an “un-doped” region) of the body of the transparenthigh-resistivity layer 604. 0

The foregoing description of the embodiment depicted in FIGS. 5A-6C, andvarious alternatives thereof and variations thereto are presented,generally, for purposes of explanation, and to facilitate a thoroughunderstanding of the detailed embodiments presented herein. However, itwill be apparent to one skilled in the art that some of the specificdetails presented herein may not be required in order to practice aparticular described embodiment, or an equivalent thereof.

Accordingly, it is understood that the foregoing and followingdescriptions of specific embodiments of a high-resistivity layer formedby low-conductivity material doped with high-conductivity material (orthe reverse) are presented for the limited purposes of illustration anddescription. These descriptions are not targeted to be exhaustive or tolimit the disclosure to the precise forms recited herein. To thecontrary, it will be apparent to one of ordinary skill in the art thatmany modifications and variations are possible in view of the aboveteachings.

FIGS. 7-9 depict flow charts of various methods of forming a transparenthigh-resistivity layer. In particular, FIG. 7 depicts example operationsof a method of forming a transparent high-resistivity layer. The method700 begins at operation 702 in which a conductive layer is disposed on asubstrate. The method 700 also includes operation 704 in which one ormore separations are formed in the conductive layer to define a numberof geometrically-separated regions of conductive material. The method700 optionally includes operation 706 in which a passivation layer(e.g., outer layer) is disposed over the geometrically-separated regionsof conductive material.

FIG. 8 depicts example operations of a method of determining a dopantconcentration for a transparent high-resistivity layer. The method 800beings at operation 802 in which a molecular weight ratio between ahigh-conductivity material and an impurity/dopant material is selected.In one example, the impurity material is oxygen and thehigh-conductivity material is a metal oxide. The method 800 alsoincludes operation 804 in which a deposition pattern is determined. Themethod 800 also includes operation 806 in which the high-resistivitylayer is disposed onto a substrate.

FIG. 9 depicts example operations of a method of forming ahigh-resistivity layer. The method 900 includes operation 902 in which asubstrate surface is prepare for bonding. The preparation operation caninclude without limitation: cleaning; chemical etching; mechanicaletching; laser etching; disposing an intermediate bonding layer;electrically charging; and so on. The method 900 also includes operation904 in which a high-resistivity layer is formed on the prepared surface.The method 900 also optionally includes operation 906 in which thehigh-resistivity layer is encapsulated with a protective material.

The foregoing description of the embodiment depicted in FIGS. 7-9, andvarious alternatives thereof and variations thereto are presented,generally, for purposes of explanation, and to facilitate a thoroughunderstanding of the detailed embodiments presented herein. However, itwill be apparent to one skilled in the art that some of the specificdetails presented herein may not be required in order to practice aparticular described embodiment, or an equivalent thereof.

Thus, it is understood that the foregoing and following descriptions ofspecific embodiments of a transparent high-resistivity layer arepresented for the limited purposes of illustration and description.These descriptions are not targeted to be exhaustive or to limit thedisclosure to the precise forms recited herein. To the contrary, it willbe apparent to one of ordinary skill in the art that many modificationsand variations are possible in view of the above teachings.

In addition, one may appreciate that although many embodiments aredisclosed above, that the operations and steps presented with respect tomethods and techniques described herein are meant as exemplary andaccordingly are not exhaustive. One may further appreciate thatalternate step order or, fewer or additional steps may be required ordesired for particular embodiments.

Although the disclosure above is described in terms of various exemplaryembodiments and implementations, it should be understood that thevarious features, aspects and functionality described in one or more ofthe individual embodiments are not limited in their applicability to theparticular embodiment with which they are described, but instead can beapplied, alone or in various combinations, to one or more of the someembodiments of the invention, whether or not such embodiments aredescribed and whether or not such features are presented as being a partof a described embodiment. Thus, the breadth and scope of the presentinvention should not be limited by any of the above-described exemplaryembodiments but is instead defined by the claims herein presented.

What is claimed is:
 1. An electronic device comprising: anantireflective coating defining an interface surface configured toreceive a user input; a high-resistivity layer below the antireflectivecoating; a dielectric layer below the high-resistivity layer; and aground-shifted capacitive input sensor positioned below the dielectriclayer and configured to capacitively couple to the high-resistivitylayer to drive the high-resistivity layer to high voltage relative to asystem ground to modulate friction between the interface surface and theuser input.
 2. The electronic device of claim 1, wherein thehigh-resistivity layer comprises a body formed from a high-resistivitymaterial doped to a selected doping concentration with ahigh-conductivity material.
 3. The electronic device of claim 2, whereinthe selected doping concentration defines a dopant concentrationgradient through a thickness of the transparent high-resistivity layer.4. The electronic device of claim 3, wherein the dopant concentrationgradient exhibits a higher dopant concentration adjacent theantireflective coating and a lower dopant concentration adjacent to thedielectric layer.
 5. The electronic device of claim 2, wherein theselected doping concentration defines: a first band of a first dopantconcentration; and a second band of a second dopant concentrationdifferent from the first dopant concentration.
 6. The electronic deviceof claim 5, wherein the first band is separated from the second band byan un-doped region of the body.
 7. The electronic device of claim 5,wherein the first band is adjacent to the second band.
 8. The electronicdevice of claim 1, wherein the high-resistivity layer comprises a bodyformed from a plurality of sublayers of alternating high and lowrelative conductivity.
 9. The electronic device of claim 1, wherein thehigh-resistivity layer is substantially transparent.
 10. A methodcomprising: disposing a dielectric layer onto an outer surface of aplanar capacitive input sensor; disposing a layer of high-resistivitymaterial onto the dielectric layer, the layer of high-resistivitymaterial comprising: a first region doped with a high-conductivitymaterial to a first doping concentration; and a second region doped witha high-conductivity material to a second doping concentration differentfrom the first doping concentration; and disposing an antireflectivecoating over the layer of high-resistivity material.
 11. The method ofclaim 10, wherein the first region is separated from the second regionby an un-doped region of the high-resistivity material.
 12. The methodof claim 10, further comprising disposing an antireflective coatinglayer over the layer of high-resistivity material.
 13. The method ofclaim 10, further comprising disposing a passivation layer over thelayer of high-resistivity material.
 14. The method of claim 10, furthercomprising, prior to disposing the layer of high-resistivity material,preparing the dielectric layer to bond to the layer of high-resistivitymaterial.
 15. An electronic device comprising: a cover layer to receivea user input; a high-resistivity layer below the cover layer andcomprising a number of physically separated regions of high-conductivitymaterial; and a ground-shifted input sensor configured to capacitivelydrive the high-resistivity layer to a high voltage relative to a systemground, the ground-shifted input sensor configured positioned below thehigh-resistivity layer and configured to detect, through thehigh-resistivity layer, a change in capacitance due to the user input.16. The electronic device of claim 15, wherein the input sensor is acapacitive touch sensor configured to detect a location of a user inputrelative to a surface area of the cover layer.
 17. The electronic deviceof claim 15, wherein the cover layer is formed from glass.
 18. Theelectronic device of claim 15, wherein the number of regions ofhigh-conductivity material are separated by low-conductivity material.19. The electronic device of claim 15, further comprising a displaypositioned below the ground-shifted input sensor.
 20. The electronicdevice of claim 19, wherein the display is configured to emit lightthrough the ground-shifted input sensor, the high-resistivity layer, andthe cover layer.